Trouble With My Damson Trees

So if you have read this blog for any length of time you'll know that I love damsons. When ripe they're up there with some of my favourite fruits. One reason why I put about another 14 in this year in our new hedge in the second field. Unfortunately, other than the one in the photo above (a Merryweather - my favourite as it is a "freestone" damson), the others don't seem to be doing so well in the orchard that I planted 8 years ago . One seems to have reverted back to it's rootstock and is growing like crazy. But no fruit and very spiky. I'm not sure if I should try grafting or budding this one over to something else, or to rip it out with the digger and plant something else completely, especially as I'll have more damsons than I'll know what to do with with once the hedge as established. The second had started growing with a serious lead. Duel domancy I think it's called where it ended up growing two leaders. Unfortunately this has lead to...